Opasatika is a township in the Canadian province of Ontario, located in the Cochrane District on the Opasatika River, a tributary of the Missinaibi River. Its name is of indigenous origin, meaning "surrounded by poplar".

The main communities in the township are Opasatika and Lowther, both located along Highway 11 between Mattice and Harty. The ghost town of Reesor Siding, site of the 1963 Reesor Siding incident, is at the western edge of the township. The former Canadian Forces Station Lowther was located in the municipality.

In the 2021 Census of Population conducted by Statistics Canada, Opasatika had a population of 200 living in 101 of its 110 total private dwellings, a change of -11.5% from its 2016 population of 226. With a land area of 327.09 km (126.29 sq mi), it had a population density of 0.6/km (1.6/sq mi) in 2021.

Historical census populations – Opasatika

Year Pop. ±% 1976 740 —     1981 681 −8.0% 1986 647 −5.0% 1991 388 −40.0% 1996 349 −10.1%	Year Pop. ±% 2001 325 −6.9% 2006 280 −13.8% 2011 214 −23.6% 2016 226 +5.6% 2021 200 −11.5%
Population figures based on revised counts. Population counts are not adjusted for boundary changes. Source: Statistics Canada

Mother tongue (2021):

• English as first language: 32.5%
• French as first language: 62.5%
• English and French as first language: 2.5%
• Other as first language: 0%

• List of townships in Ontario
• List of francophone communities in Ontario

• Official website